This invention is directed generally to an orthodontic appliance, and more particularly, to one which is adapted to be adhered directly to the surface of a tooth.
In recent years, advances have been made in direct adhering orthodontic brackets for replacement of the prior art cumbersome and less desirable bands. Generally speaking, direct adhering orthodontic brackets which provide a satisfactory bond so as to enable the necessary treatment to be rendered, come in two forms. One form of bracket requires a hole penetrating the entire thickness of the base from the front to the back surface, i.e., from the contact surface to the exposed surface. These holes allow the cement to flow from the dental surface to the front surface of the base member and over the edges, thus forming the locks which hold the base member and connecting brackets to the dental surface.
Other base members are provided in the form of a wire mesh wherein the adhesive flows through the holes in the wine mesh and forms a locking bond which adheres the orthodontic appliance to the patient's tooth. A variation of the above wire mesh system is a two section base member which consists of a hard metal sheet welded over a wire screen material, the assembly of which is welded to the bracket.
Certain disadvantages are however, present even with these more advanced systems. For instance, in these systems the base member must provide a maximum surface area which makes the appliance highly conspicuous and thus esthetically unpleasing. Moreover, certain problems arise in attempting to adhere such a member to smaller size teeth or partially erupted teeth. With these prior art systems, the orthodontist must be careful to insure that he has placed a sufficient amount of cement on the bracket so that it overflows and forms a locking relation. Failure to do so will result in a poor bond. Also, with these prior art appliances excess cement, if allowed to remain, forms food traps. In practice, the cement is feathered; this procedure must be performed carefully or else the cement will be excessively removed and the bond weakened. On the other hand, if excessive cement remains on the exposed surface of the base member, it may lock the tie wing areas of the bracket or interfere with the arch wires. It has also been found in practice that the cement exposed on the base member surface tends to darken with age. Some of this darkening is due to normal aging, some due to staining from food, tobacco, coffee and other liquids. Also, plaque and fungus like growth has sometimes been found growing on the surface of the exposed cement. Moreover, the irregular nature of the exposed cement acts as a food trap and so contributes to the formation of caries.
By the means disclosed herein, an orthodontic appliance is provided which may be directly adhered to the surface of a tooth and which has superior bonding without the above disadvantages encountered in the prior art systems.